Heim  >  Artikel  >  Datenbank  >  MySQLDBCPExample_MySQL

MySQLDBCPExample_MySQL

WBOY
WBOYOriginal
2016-06-01 13:02:381343Durchsuche

0. Introduction

Versions of MySQL and JDBC drivers that have been reported to work:

MySQL 3.23.47, MySQL 3.23.47 using InnoDB,, MySQL 3.23.58, MySQL 4.0.1alphaConnector/J 3.0.11-stable (the official JDBC Driver)mm.mysql 2.0.14 (an old 3rd party JDBC Driver)

Before you proceed, don't forget to copy the JDBC Driver's jar into $CATALINA_HOME/lib.

1. MySQL configuration

Ensure that you follow these instructions as variations can cause problems.

Create a new test user, a new database and a single test table. Your MySQL user must have a password assigned. The driver will fail if you try to connect with an empty password.

\ \ \
\
mysql> GRANT ALL PRIVILEGES ON *.* TO javauser@localhost 
    ->   IDENTIFIED BY 'javadude' WITH GRANT OPTION;
mysql> create database javatest;
mysql> use javatest;
mysql> create table testdata (
    ->   id int not null auto_increment primary key,
    ->   foo varchar(25), 
    ->   bar int);
\
\ \ \
Note: the above user should be removed once testing is complete!

Next insert some test data into the testdata table.

\ \ \
\
mysql> insert into testdata values(null, 'hello', 12345);
Query OK, 1 row affected (0.00 sec)

mysql> select * from testdata;
+----+-------+-------+
| ID | FOO   | BAR   |
+----+-------+-------+
|  1 | hello | 12345 |
+----+-------+-------+
1 row in set (0.00 sec)

mysql>
\
\ \ \

2. Context configuration

Configure the JNDI DataSource in Tomcat by adding a declaration for your resource to your Context.

For example:

\ \ \
\
<Context>

    <!-- maxActive: Maximum number of database connections in pool. Make sure you
         configure your mysqld max_connections large enough to handle
         all of your db connections. Set to -1 for no limit.
         -->

    <!-- maxIdle: Maximum number of idle database connections to retain in pool.
         Set to -1 for no limit.  See also the DBCP documentation on this
         and the minEvictableIdleTimeMillis configuration parameter.
         -->

    <!-- maxWait: Maximum time to wait for a database connection to become available
         in ms, in this example 10 seconds. An Exception is thrown if
         this timeout is exceeded.  Set to -1 to wait indefinitely.
         -->

    <!-- username and password: MySQL username and password for database connections  -->

    <!-- driverClassName: Class name for the old mm.mysql JDBC driver is
         org.gjt.mm.mysql.Driver - we recommend using Connector/J though.
         Class name for the official MySQL Connector/J driver is com.mysql.jdbc.Driver.
         -->
    
    <!-- url: The JDBC connection url for connecting to your MySQL database.
         -->

  <Resource name="jdbc/TestDB" auth="Container" type="javax.sql.DataSource"
               maxActive="100" maxIdle="30" maxWait="10000"
               username="javauser" password="javadude" driverClassName="com.mysql.jdbc.Driver"
               url="jdbc:mysql://localhost:3306/javatest"/>

</Context>
\
\ \ \

3. web.xml configuration

Now create a WEB-INF/web.xml for this test application.

\ \ \
\
<web-app xmlns="http://java.sun.com/xml/ns/j2ee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
    version="2.4">
  <description>MySQL Test App</description>
  <resource-ref>
      <description>DB Connection</description>
      <res-ref-name>jdbc/TestDB</res-ref-name>
      <res-type>javax.sql.DataSource</res-type>
      <res-auth>Container</res-auth>
  </resource-ref>
</web-app>
\
\ \ \

4. Test code

Now create a simple test.jsp page for use later.

\ \ \
\
<%@ taglib uri="http://java.sun.com/jsp/jstl/sql" prefix="sql" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>

<sql:query var="rs" dataSource="jdbc/TestDB">
select id, foo, bar from testdata
</sql:query>

<html>
  <head>
    <title>DB Test</title>
  </head>
  <body>

  <h2>Results</h2>
  
<c:forEach var="row" items="${rs.rows}">
    Foo ${row.foo}<br/>
    Bar ${row.bar}<br/>
</c:forEach>

  </body>
</html>
\
\ \ \

That JSP page makes use of JSTL's SQL and Core taglibs. You can get it from Apache Tomcat Taglibs - Standard Tag Library project — just make sure you get a 1.1.x release. Once you have JSTL, copy jstl.jar andstandard.jar to your web app's WEB-INF/lib directory.

Finally deploy your web app into $CATALINA_BASE/webapps either as a warfile called DBTest.war or into a sub-directory called DBTest

Once deployed, point a browser at http://localhost:8080/DBTest/test.jsp to view the fruits of your hard work.

Stellungnahme:
Der Inhalt dieses Artikels wird freiwillig von Internetnutzern beigesteuert und das Urheberrecht liegt beim ursprünglichen Autor. Diese Website übernimmt keine entsprechende rechtliche Verantwortung. Wenn Sie Inhalte finden, bei denen der Verdacht eines Plagiats oder einer Rechtsverletzung besteht, wenden Sie sich bitte an admin@php.cn